Our aim is to demonstrate how agent-based models can play an important role in understanding sustainability. Here, we describe how the agent-based motivation models support the description of desirable outcomes and help to develop relevant and shared high-level goals in particularly complex areas such as sustainability. We focus on sustainable behaviour in households, and how to provide guidance for people to behave in a more environmentally-friendly manner. Our example demonstrates that the agent-based models are able to focus on the right questions when making decisions between alternatives in this multifaceted domain. With agent-based models, we aim to enable people to make the right choices for their particular circumstances and values. The agent paradigm is uniquely suited to understanding and representing the relevant goals, quality goals, and individual activities.